Technical Field
The present disclosure generally relates to wearable heads-up displays, and more particularly, to calibration systems and methods for eye tracking systems of wearable heads-up displays.
Description of the Related Art
Wearable Heads-Up Displays
A head-mounted display is an electronic device that is worn on a user's head and, when so worn, secures at least one electronic display within a viewable field of at least one of the user's eyes, regardless of the position or orientation of the user's head. A wearable heads-up display is a head-mounted display that enables the user to see displayed content but also does not prevent the user from being able to see their external environment. The “display” component of a wearable heads-up display is either transparent or at a periphery of the user's field of view so that it does not completely block the user from being able to see their external environment. Examples of wearable heads-up displays include: the Google Glass®, the Optinvent Ora®, the Epson Moverio®, and the Sony Glasstron®, just to name a few.
The optical performance of a wearable heads-up display is an important factor in its design. When it comes to face-worn devices, however, users also care a lot about aesthetics. This is clearly highlighted by the immensity of the eyeglass (including sunglass) frame industry. Independent of their performance limitations, many of the aforementioned examples of wearable heads-up displays have struggled to find traction in consumer markets because, at least in part, they lack fashion appeal. Most wearable heads-up displays presented to date employ large display components and, as a result, most wearable heads-up displays presented to date are considerably bulkier and less stylish than conventional eyeglass frames.
A challenge in the design of wearable heads-up displays is to minimize the bulk of the face-worn apparatus while still providing displayed content with sufficient visual quality. There is a need in the art for wearable heads-up displays of more aesthetically-appealing design that are capable of providing high-quality images to the user without limiting the user's ability to see their external environment.
Eye Tracking
Eye tracking is a process by which the position, orientation, and/or motion of the eye may be measured, detected, sensed, determined (collectively, “measured”), and/or monitored. In many applications, this is done with a view towards determining the gaze direction of a user. The position, orientation, and/or motion of the eye may be measured in a variety of different ways, the least invasive of which typically employ one or more optical sensor(s) (e.g., cameras) to optically track the eye. Common techniques involve illuminating or flooding the entire eye, all at once, with infrared light and measuring reflections with at least one optical sensor that is tuned to be sensitive to the infrared light. Information about how the infrared light is reflected from the eye is analyzed to determine the position(s), orientation(s), and/or motion(s) of one or more eye feature(s) such as the cornea, pupil, iris, and/or retinal blood vessels.
Eye tracking functionality is highly advantageous in applications of wearable heads-up displays. Some examples of the utility of eye tracking in wearable heads-up displays include: influencing where content is displayed in the user's field of view, conserving power by not displaying content that is outside of the user's field of view, influencing what content is displayed to the user, determining where the user is looking or gazing, determining whether the user is looking at displayed content on the display or through the display at their external environment, and providing a means through which the user may control/interact with displayed content.